1. Field of the Invention
This invention relates to an ink jet recording head, and more particularly to an ink jet recording head which is capable of harmonious recording.
2. Related Background Art
The ink jet recording methods have numerous advantages such as the very small noise during recording, ease of color recording and the capability of recording on so-called plain paper, and have been attracting more and more attention in recent years. Above all, the ink jet recording method whereby heat energy is imparted to liquid to produce bubbles in the liquid and the liquid is discharged from an opening by an abrupt variation in the volume of the bubbles to thereby accomplish recording, that is, the ink jet recording method utilizing heat energy, has specially been drawing attention because of the ease with which the apparatus is made compact and the possibility of disposing openings at high density.
Although, the ink jet recording method utilizing heat energy, because it utilizes for discharge a variation in the volume of gas from the production to the extinction of bubbles, can readily cause liquid to be accurately discharged in response to a recording signal, it has sometimes encountered difficulty in accurately controlling the amount of discharged liquid over a wide range and at multiple stages.
So, an ink jet recording head in which a plurality of heat energy generating members are provided for a single discharge port (opening) for liquid discharge and the plurality of heat energy generating members are driven individually or at the same time to thereby accomplish harmonious recording is proposed, for example, in U.S. Pat. No. 4,251,824. However, such a plurality of heat energy generating members, which are provided in a liquid path as a heat generating portion leading to the opening, must be arranged in the direction of extension of the liquid path (the direction of discharge) because the liquid path is minute. Accordingly, the positions of the heat energy generating members with respect to the opening differ from one another, and this has sometimes given rise to a problem in respect of the liquid discharge efficiency. Particularly, when the recording head has been left unused for a while and the viscosity of the liquid near the opening has increased, there has arisen the problem that reliable liquid discharge does not take place when recording is resumed.